Method for etching a micropatterned microdepot prosthesis

Abstract

An implantable prosthesis, for example a stent, is provided having one or more micropatterned microdepots formed in the stent. Depots are formed in the prosthesis via chemical etching and laser fabrication methods, including combinations thereof. They are formed at preselected locations on the body of the prosthesis and have a preselected depth, size, and shape. The depots can have various shapes including a cylindrical, a conical or an inverted-conical shape. Substances such as therapeutic substances, polymeric materials, polymeric materials containing therapeutic substances, radioactive isotopes, and radiopaque materials can be deposited into the depots.

What is claimed is:  
     
       1. A method of forming depots on an implantable prosthesis comprising: 
       providing a prosthesis having a surface applying  
       applying a first fluid onto said surface, said first fluid forming a protective coating on said surface;  
       generating a mask having transparent and opaque areas, said transparent areas representing said depots;  
       illuminating said mask, wherein a light passes through said transparent areas forming exposed metal areas on said surface of said prosthesis;  
       applying a second fluid to said prosthesis, wherein said second fluid dissolves said exposed metal areas to a predetermined depth, forming depots;  
       removing said second fluid so that a quantity of said fluid remains within said depots, said fluid expanding the size and volume of said depots so as to provide conically shaped depots having a closed end and an open end, wherein the diameter of the open end is smaller than the diameter of the closed end;  
       removing said quantity of said second fluid; and  
       rinsing said prosthesis in a third fluid to remove said protective coating.  
     
     
       2. The method according to  claim 1 , wherein during said act of illuminating said mask said first fluid undergoes a photochemical reaction. 
     
     
       3. The method according to  claim 1 , wherein said first fluid forms a photoresist coating. 
     
     
       4. The method according to  claim 1 , wherein said second fluid is a ferric chloride solution. 
     
     
       5. The method according to  claim 1 , wherein said third fluid is methylene chloride. 
     
     
       6. The method according to  claim 1 , wherein said light is ultraviolet light. 
     
     
       7. The method according to  claim 1 , wherein said light is laser light. 
     
     
       8. The method according to  claim 7 , wherein said laser light is generated from an excimer laser. 
     
     
       9. The method according to  claim 1 , wherein said depots are evenly distributed throughout the body of said prosthesis and the volume of said depots is generally the same. 
     
     
       10. The method according to  claim 1 , wherein the volume of each of said depots is greater at the ends of said prosthesis as compared to the midsection of said prosthesis. 
     
     
       11. A method for forming depots on an implantable prosthesis, comprising: 
       providing a prosthesis having a surface;  
       applying a first fluid onto said surface, said first fluid forming a protective coating on said surface;  
       selectively ablating portions of said protective coating with a laser;  
       drilling into said prosthesis with said laser to form depots;  
       applying a second fluid to said prosthesis, wherein said second fluid expands the size and volume of said depots to provide a conically shaped depot having an open end and a closed end, wherein the diameter of the closed end is larger than the diameter of the open end;  
       removing said second fluid; and  
       rinsing said prosthesis in a third fluid to remove said protective coating.  
     
     
       12. The method according to  claim 11 , wherein said laser is an UV laser. 
     
     
       13. The method according to  claim 11 , wherein said laser is an excimer laser. 
     
     
       14. The method according to  claim 11 , wherein said laser is a Nd:YAG laser. 
     
     
       15. The method according to  claim 11 , wherein the volume of each of said depots is greater at the ends of said prosthesis as compared to the midsection of said prosthesis.